Two stage absorption refrigeration machine with flash gas and carryover control in second stage generator



NOV. 17, 1970 PORTER ETAL 3,540,231

TWO STAGE ABSORPTION REFRIGERATION MACHINE WITH FLASH GAS AND CARRYOVER CONTROL IN SECOND STAGE GENERATOR Filed Dec.. 20, 1968 2 Sheets-Sheet 1 fi s5 63 FIG. l

s5 FIG. 2

L 2 INVENTORS 82 JAMES M. PORTER 74 BY CARL v. LOWETH Nov. 17, 1970 J. M. PORTER ETAL 3,540,231

TWO STAGE ABSORPTION REFRIGERATION MACHINE WITH FLASH GAS AND CARRYOVER CONTROL IN SECOND STAGE GENERATOR Filed Dec. 20, 1968 2 Sheets-Sheet 2 FIG. 4

OWETH INVE/VT'OHS. JAMES M. PORTER CARL V.

United. States Patent TWO STAGE ABSORPTION REFRIGERATION MACHINE WITH FLASH GAS AND CARRY- OVER CONTROL IN SECOND STAGE GENERATOR James M. Porter, La Crosse, and Carl V. Loweth, Onalaska, Wis, assignors to The Trane Company, a corporation of Wisconsin Filed Dec. 20, 1968, Ser. No. 785,511 Int. Cl. F25b /06 US. Cl. 62-495 7 Claims ABSTRACT OF THE DISCLOSURE The structural relationship of a two stage generator absorption refrigeration machine is disclosed. A primary shell contains a low pressure generator, a condenser, an evaporator, and an absorber. A separate shell contains a high pressure generator. The low pressure generator includes flash gas and carryover control baflles.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a refrigeration machine, and more particularly, to a two stage generator absorption refrigeration machine containing an improved low pressure generator construction.

Description of the prior art Two stage absorption refrigeration machines contain a first stage high pressure generator and a second stage low pressure generator for concentrating absorbent solution and liberating refrigerant in the form of vapor. This Vapor is then condensed and reevaporated to chill a fluid which is circulated to a heat load. The evaporated refrigerant is absorbed by an absorbent solution. The diluted absorbent solution is circulated to the first stage generator for partial concentration. It is further concentrated in the second stage generator.

The first stage generator operates at a substantially higher pressure than does the second stage generator. The partially concentrated solution leaving the first stage generator has a. tendency to flash or partially vaporize when it enters the lower pressure second stage generator. The vapor produced when the partially concentrated solution flashes entrains some liquid absorbent solution which is carried over into the condenser. This liquid, of course, contains absorbent, the presence of which is undesirable in the condenser.

SUMMARY OF THE INVENTION This invention therefor provides an absorption refrigeration machine including an absorber section, an evaporator section, a condenser section, a first stage high pressure generator section, and a second stage low pressure generator section. The improvement in this refrigeration machine comprises: a conduit means for feeding intermediate strength absorbent solution to the low pressure generator section from the high pressure generator section, wall and floor means forming low pressure generator section, and a first bafile within the low pressure generator section spaced from the inlet of the conduit means. The wall means contains an eliminator means which places the condenser section and the low pressure generator section in vapor communication. The first baffle intersects the longitudinal axis of the inlet of the conduit means.

The first baffle preferably has a first opening above the longitudinal axis of the inlet to allow vapor to pass beyond the baffle and a second opening below the longitudinal axis to allow liquid to travel past the first bafl le.

'ice.

Preferably, the improvement includes a second baffle positioned in a path between first opening in the first bafile and the eliminator means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of the absorption refrigeration machine of the present invention.

FIG. 2 is a rear View of the absorption refrigeration machine of FIG. 1.

FIG. 3 is a front view of the absorption refrigeration machine of FIG. 1 in which the front tube sheets of the primary and first stage generator shells have been omitted. The external piping has also been deleted for simplicity.

FIG. 4 is a side view of the primary shell taken along section A-A of FIG. 3.

FIG. 5 is a partial cross sectional front elevation view of the primary shell taken along section BB of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring jointly to FIGS. 1, 2, and 3, the absorption refrigeration machine comprises a first fluid tight shell 10 which encloses a condenser section 12, an evaporator 14, an absorber 16, and a second stage generator, low pressure 20. A second fluid tight shell 35 encloses the first stage, high pressure generator 18.

The absorber 16 has a heat exchanger, comprising longitudinally extending tubes 22, which is supplied with cooling fluid from a source not shown through header 24. Connection with the conduit from the cooling fluid source is made with flange 25. Header 24 supplies all of tubes 22. The cooling fluid, which can be water which is evaporatively cooled by air, is conducted from header 33 by conduit 26 from the rear of the heat exchange tubes 22 to a header 27 which supplies heat exchange tubes 28 in condenser 12. Connection of conduit 26 with headers 33 and 27 is made by means of flanges 32 and 34, respectively. A wall 29 substantially encloses the condenser section. The cooling fluid leaves the condenser through header 30 and returns to the cooling fluid source via a conduit (not shown) connected to flange 31. It is understood, of course, that any of a variety of connections may be made with the heat exchangers of this machine without departing from the inventive concept; for example, heat exchangers 22 and 28 can be independently connected to a source of cooling fluid, and each can be altered to produce a twopass effect.

High pressure steam, or other heating medium, flows from a source, such as a boiler (not shown), into header 52 by connection with flange 36. The steam flows from header 52 into heat exchange tubes 37 in high pressure generator 18. End plate 38 has a dual function; it serves not only as the end plate which seals the ends of shell 35, but also is the tube sheet for heat exchange tubes 37. End plate 39 serves the same purpose at the opposite end of the generator 18 and additionally provides connection with conduit 40. Heat exchange tubes 37 terminate within end plate 39 and in fluid communication with header 41. A restrictor means is normally attached to flange 42 to prevent escape of steam from the heat exchange tubes 37 until it has condensed, allowing essentially only condensate to leave the heat exchange tubes 37 through connection 42. This restrictor means can be any suitable steam flow restrictor such as an orifice or a float valve. Alternatively, the restrictor can be mounted within the generator 12.

Heat from condensing steam in the heat exchange tubes 37 causes dilute absorbent solution present in the first stage generator to boil. The steam condensate from the aforementioned restrictor means flows back to the steam generating source. It is to be understood, of course, that any other suitable heat source can be substituted for the first stage generator heat exchanger without substantially modifying the principals of construction of this invention.

Various types of refrigerants and absorbents may be used in the present machine. A solution of lithium bromide absorbent in a refrigerant such as water is satisfactory. Other suitable absorbents and refrigerants may be used if desired. The term concentrated solution as used herein means a solution which is concentrated in an absorbent. A Weak solution is a solution dilute in absorbent. A solution having a concentration between that of a concentrated solution and a weak solution is termed as intermediate strength solution.

The refrigerant vapor generated in the first stage generator 1-8 flows through conduit 40 and into the second stage low pressure generator 20. Conduit 40 is connected to flanges 52 and 53, the latter of which allows access to header 43. The refrigerant vapor flows from header 43 into heat exchange tubes 44. The refrigerant vapor condenses and releases heat to further concentrate intermediate strength solution present in the second stage generator 20. A flow regulating device in the form of an orifice or a trap 45 regulates the flow of refrigerant from the heat exchange tubes 44 into the condenser 12.

Trap 45 is connected with heat exchange tubes 44 via header 46 onto which it is attached at flange 47. Refrigerant condensed in heat exchange tubes 44 enters the condenser 12 at a connection 48 above header 30. The difference in pressure between the condenser and heat exchange tubes 44 forces the condensed refrigerant from the tubes 44 into the condenser. Trap 45 functions to prevent flow of any refrigerant vapor from heat exchange tubes 44 into the condenser 12. The vapor produced from the boiling intermediate strength solution in the second stage generator passes through liquid eliminator 49 where it is condensed into a liquid in condenser 12. The total liquid refrigerant flows from the condenser through opening or orifice 50 into evaporator 14.

The liquid refrigerant is evaporated in evaporator 14, thus removing heat from the fluid in heat exchange tubes 61. The refrigerant vapor produced passes through liquid eliminators 62 and into the absorber section 16. Unevaporated liquid refrigerant is collected in pan 60 from which it enters conduit 63 and is recirculated by pump means 64 through conduit 65 into spray header 66. From header 66 the liquid refrigerant is sprayed over heat exchange tubes 61 through spray nozzles 67. Fluid from a heat load is circulated through heat exchange tubes 61 by connection with flanges 70 and 71 on headers 87 and '88. The fluid circulated through heat exchange tubes 61 is cooled by the evaporating refrigerant. It is thereafter returned to the heat load.

Absorbent solution present in absorber 16 absorbs refrigerant vapor produced in evaporator 14. The solution from the absorber 16 flows through a conduit 72 in the bottom of the absorber section. The absorbent solution from conduit 72 is circulated by pump 73 through conduit 74, a low temperature heat exchanger 75, a high temperature heat exchanger 76, and conduit 77 from which it enters high temperature generator 18. The absorbent solution flowing into generator 18 is partially concentrated therein.

The partially concentrated solution from high temperature generator 18 flows through conduit 78 to high temperature heat exchanger 76 in which it gives up heat to weak solution flowing into conduit 77. It then flows through conduit 79 into low temperature generator 20, in which it is further concentrated. The concentrated solution from the second stage generator 20 flows through conduit 80), through low temperature heat exchanger 75 into conduit 81 which is connected to the inlet of pump 82. Dilute solution flowing from absorber 16 through conduit 83 also enters the inlet of pump 82 where it is mixed with the concentrated solution flowing from conduit 81. The weak and concentrated solutions are mixed in pump 82 and are forced through conduit 84 to spray header 85, from which it is distributed over heat exchange tubes 22 by spray nozzles 86.

It will be understood by one skilled in the absorption refrigeration art that motive power is necessray to drive pumps 64, 73, and 82. The preferred power source is, of course, an electric motor. Each pump can be driven by a separate motor, or a single motor can be employed to drive all pumps with a single shaft.

Referring now to FIGS. 3, 4, and 5, the internal arrangement of the component sections of the absorption machine will be further described. The repetitive numerals used in FIGS. 4 and 5 correspond to those utilized in the preceding figures. High temperature generator 18 can have a length equal to that of main shell 10. In this embodiment generator shell 35 has an upper circular section and a lower liquid tank section 91. Partially concentrated absorbent solution is collected in tank 91 before it flows into conduit 78. Refrigerant vapor produced in high pressure generator 18 flows through opening 54 into conduit 40. Intermediate strength solution flows into low pressure generator 20 through conduit 79.

Concentrated solution flows out of low pressure generator 20 through weir 92 in wall 101 into compartment 93. From this compartment the concentrated absorbent solution flows into conduit 80. Compartment 93 is enclosed by walls and 101 and by bottom plate 102. The liquid eliminators 49 are a series of spaced V-shaped plates positioned as shown in FIGS. 3 and 4 so that the edges 116 of one plate overlap the V-intersection 117 of the next adjacent plate. This construction provides a tortuous path for refrigerant vapor to enter the condenser facilitating removal of entrained liquid refrigerant.

It will be noted that all of the heat exchange tubes are longitudinally extending relative to the main shell 10 and generator shell 35. End plates 94 and 95 attached at the ends of shell 10 serve a dual function. They seal and form the end portions of the various compartments within the shell. Furthermore, the heat exchange tubes extend through to the outside of end plates 94 and 95. Thus the end plates form the tube sheets for all of the heat exchangers in primary shell 10. The headers 24, 27, 30, 33, 43, 46, 68 and 69 are mechanically attached to the end plates for distributing the various fluids through the heat exchange tubes.

The second stage generator receives partially concentrated solution from the first stage high pressure generator through conduit 79. FIG. 5 illustrates the rear portion of low pressure generator 20' taken along section B--B of FIG. 4. Baflle is positioned in spaced relationship to the inlet 111 of conduit 79. As the partially concentrated, intermediate strength absorbent solution enters the low pressure generator from the high pressure generator, the pressure reduction will cause it to flash, producing a vapor in which liquid absorbent solution is entrained. Bafllle 110 intersecting the longitudinal axis (indicated on baffle 110 by point of the inlet 111 prevents the flashing absorbent solution from carrying across low pressure generator 20 and inhibits the flow of entrained liquid through eliminators 49. Baflle 110 has an opening 113 in its upper portion which allows vapor and some entrained liquid to pass beyond baffle 110. An additional opening 114 is included in the lower portion of baflle 110 to allow free flow of absorbent solution from the inlet 111 to the area of low pressure generator 20 occupied by heat exchange tubes 44. An additional baflle 112 is placed in the path between eliminators 49 and opening 113 of battle 110. Vapor and entrained liquid passing through opening 113 will impinge upon baflie 112. Since baffle 112 is attached to the roof (primary shell 10) of the low pressure generator 20, this vapor must pass below baflle 112 to enter eliminators 49. Substantially all of the liquid absorbent solution entrained in the flash vapor is removed by baflle 112. It will be noted that baflies 110 and 112 do not extend the full length of evaporator 20 as the area near inlet 111 is the only portion of evaporator 20 effected by the flash problem.

The absorber section 18 is in vapor communication with the evaporator section 14. Condenser 12 is in liquid communication with the evaporator section 14 through the orifice 50. The condenser 12 receives refrigerant liquid from heat exchange tubes 44 via connection 48 and is also in vapor communication with the low pressure generator 20 through liquid eliminators 49. The relative arrangement of the sections as shown in FIG. 3 are preferred, that is, the low pressure generator and condenser substantially horizontally contiguous in the upper portion of the main shell, the absorber in the lower portion of the main shell, and the evaporator above the absorber. The high pressure generator is preferably located to provide a liquid level therein above any liquid level existing in the main shell. However, other arrangements of the low pressure generator, the condenser, the evaporator, and the absorber within the main shell can be made without departing from the present invention. Of course, the shells 10 and 35 need not be of the cylindrical cross section as shown. They may be of any desired cross section; however, the cylindrical shape is most desirable.

Flow, pressure, safety, and miscellaneous control is necessary for proper operation of the absorption refrigeration machine disclosed above. For an example of an appropriate control mechanism for the instant machine, refer to the copending application, Ser. No. 785,512, filed Dec. 20, 1968, the disclosure of which is incorporated herein by reference.

The utility and need for the generator construction of this invention are apparent from the foregoing description. Therefore, what is claimed is:

1. An absorption refrigeration machine including an absorber section, an evaporator section, a condenser section, a high pressure generator section, and a low pressure generator section, the improvement therein comprising:

(a) conduit means for feeding intermediate strength absorbent solution to said low pressure generator section from said high pressure generator section,

(b) wall and floor means forming said low pressure generator section, said wall means containing eliminator means placing said contenser section and said low pressure generator section in vapor communication,

(c) a first bafile within said low pressure generator section spaced from the inlet of said conduit means, said bafile intersecting the longitudinal axis of the inlet of said conduit means.

2. The machine of claim 1 wherein said bafiie has a first opening above said axis for passage of vapor.

3. The machine of claim 2 wherein said baffle has a second opening below said axis for passage of liquid.

4. The machine of claim 2 additionally comprising a second baflie positioned in a path between said first opening and said eliminator means.

5. The machine of claim 3 wherein said inlet of said conduit means is positioned so that its said axis is substantially in a horizontal plane.

6. The machine of claim 5 wherein said first baffie is positioned substantially in a vertical plane.

7. The machine of claim 6 wherein said second bafile is positioned substantially in a vertical plane.

References Cited UNITED STATES PATENTS 3,003,931 10/1961 Worthen et al. 202-197 X 3,266,266 8/1966 Reid 62497 X WILLIAM E. WAYNER, Primary Examiner US. 01. X.R. 62-497; 2024 97 

